With the advent of deregulation of the telephone industry and the ownership of telephone equipment by subscribers to telephone service, a need has arisen to define a point of demarcation between the portion of the telephone network owned by the subscriber and the portion which is owned by the telephone company. This need has been met through the use of a telephone network interface device that is disposed adjacent to the subscriber's home or place of business.
In one form, an interface device can include a first set of terminal posts that receives wires from the central office of the telephone company and a second set that receives wires from the subscriber's home or place of business. These two sets of posts are linked together with equipment such as a standard RJ-11C modular plug and jack assembly (which can also have one of the sets of posts disposed on it). The plug and jack assembly establishes an interface between the subscriber's portion of the telephone system and the portion that belongs to the company. The equipment, such as the RJ-11C jack and plug assembly, and the associated terminal posts, are convenient for the subscriber to use and easy for the telephone company to install and maintain. All of this equipment is mounted inside of a molded plastic case or housing that is installed at the subscriber's site.
The use of the telephone interface devices in the telephone system has provided an opportunity for the telephone companies to install electronic circuit boards that are necessary for the maintenance and testing of the telephone equipment. These circuit boards can be installed in the case or housing in which the plug and jack assemblies are disposed. For example, circuit boards with testing circuits such as the so-called half ringer circuit or equivalent (which allows a telephone company to test the integrity of its wires and circuits without visiting the subscriber's location) can be disposed in the case that holds the telephone interface device.
The boards that are used for such circuits contain the usual array of wires, resistors, transistors and other electronic components. Because of improvements and modifications that are made to the circuits, the size and shape of the circuit boards may change from time to time, typically becoming smaller as they are improved or simplified.
Thus, since the size and shape of the circuit boards may change from time to time, it is necessary to provide for an accommodation of these future changes without having to make modifications in the shape and size of the molded plastic case itself. Since the molded plastic case is affixed to a building or other similar type of support, it is quite undesirable to have to change the entire case that houses the interface device merely because a circuit board that has to be mounted in it has been changed in size from that which was in use when the case was molded.
We have discovered that through the use of the carrier of the present invention, circuit boards of many different sizes and shapes can be accommodated in the case for the telephone network interface device without making changes in the size and shape of the molded case. The circuit board carrier that we have discovered eliminates the need for costly modifications to the mold that is used in the process of making the case for the interface device. Relatively inexpensive carriers can be made easily to accommodate changes in the size and shape of the circuit boards that will be placed into the case of the telephone interface device over the years. The carrier can be molded from the same plastic, if desired, as the case into which it will be fitted.
Moreover, in many cases, it is highly desirable to use the carrier of the present invention not only for receiving the circuit boards, but also as an integral part of the interface device itself, in that we have discovered the carrier can serve as a support to provide wiring locations for circuit boards that are in use within the case. For example, the carrier of the present invention can have pre-formed fittings for threaded fasteners which can serve as electrical posts in the interface device, thereby providing not only a carrier for the circuit board, but also an interactive terminal in the telephone system. This feature can be provided without losing enclosure space or making costly modifications to the mold as the size and shape of the circuit boards varies from time to time.